[Bug analyzer/109201] New: GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0

[Bug analyzer/109201] New: GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0

[geoffreydgr at icloud dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109201

            Bug ID: 109201
           Summary: GCC Static Analyzer does not generate a div-by-zero
                    warning for the `if ((d.b = 1) / f)` where `f` is 0
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: geoffreydgr at icloud dot com
  Target Milestone: ---

GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b =
1) / f)` statement, but if it is changed to `if ((d.b = 1) / 0)`, analyzer
generates that warning.

 See it live: https://godbolt.org/z/3f18j9az7

Input:
```c
void __analyzer_eval();

struct a
{
    int b : 6;
} c()
{
    struct a d;
    int e = 2;
    int f = 0;
    if ((d.b = 1) / f)
        if (1 >= d.b <= e)
        {
            __analyzer_eval(0 >= d.b <= e);
        }
}

```

Output:
```
<source>: In function 'c':
<source>:15:13: warning: TRUE
   15 |             __analyzer_eval(0 >= d.b <= e);
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Compiler returned: 0
```

[Bug analyzer/109201] GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109201

--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
The division by zero warning on:
   if ((d.b = 1) / 0)
is from -Wdiv-by-zero, which isn't from the analyzer (
https://godbolt.org/z/433PhKhvM )

The analyzer currently only implements -Wanalyzer-tainted-divisor for
attacker-controlled values used in division; it doesn't check for zero itself.

So this seems like more of an RFE: it sounds like you'd want the analyzer to
complain about known zero values reaching a division, as a souped-up kind
implementation of the existing -Wdiv-by-zero.

[Bug analyzer/109201] GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109201

--- Comment #2 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
*** Bug 109200 has been marked as a duplicate of this bug. ***

[Bug analyzer/109201] GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109201

David Malcolm <dmalcolm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
We already have PR 99669 as an RFE for this; marking as a dup.

*** This bug has been marked as a duplicate of bug 99669 ***